Epidemiology of diseases caused by Streptococcus pyogenes in Serbia during a nine-year period (1991-1999).

BACKGROUND & OBJECTIVES Streptococcus pyogenes (group A Streptococcus - GAS) is an important human pathogen which causes a variety of diseases, including tonsillopharyngitis, scarlet fever and rheumatic fever. It is important to understand the changes in epidemiology of the diseases caused by the pathogen for improved control of such infections. Hence, the aim of the present study was to carry out an epidemiological analysis of GAS infections in Serbia in a 9-yr period (1991-1999) and evaluation of susceptibility of GAS isolates obtained during the same period to penicillin and erythromycin. METHODS Occurrence of tonsillopharyngitis, scarlatina and rheumatic fever was analyzed and GAS carrier status in healthy children was examined over a 9-yr period from 1991 to 1999. Susceptibility to penicillin and erythromycin was determined for 1657 GAS isolates obtained from patients diagnosed with pharyngitis or scarlet fever and 512 isolates from healthy carriers. M-type antigen was also determined in these isolates. RESULTS The average incidences of tonsillopharyngitis and scarlet fever were 76.2 and 30.8 per cent respectively. A total of 166 cases of rheumatic fever were registered. Per cent of carriers varied from 5.5 to 11.4 per cent over the study period. Predominating M serotypes among GAS isolates tested were M1, M3, M4, M6, M11, M12 and M18, depending on the source of clinical material and period of isolation. Antimicrobial susceptibility testing showed susceptibility to penicillin in all isolates tested and resistance to erythromycin in 2.41 per cent of the isolates. INTERPRETATION & CONCLUSION Although the fluctuations in incidence were noted during the nine-year period, the incidence of streptococcal tonsillopharyngitis is low but with a steady raise in Serbia. No significant changes in the incidence of scarlet fever and rheumatic fever were noted. Susceptibility to penicillin remained unchanged, but the number or erythromycin resistant strains have increased.